Problem : VCF no auto-oscillation

Hi everyone,

I can’t get auto-oscillation from the filter… :frowning:

The resonance is not “biting” as in the demos. It’s quite weak. I tried to adjust the V/oct trimmer but it didn’t help at all.

Any suggestion ?

Thank you

Maybe some resistor values swapped somewhere? Or maybe you used the wrong kind of pot (10k linear instead of 100k audio) for the resonance?

Thank you for your time and answer.

I’ve checked all the pots and I have only one 100k pot on the Volume control. The others are all 10k. The kit must have contained only one 100k pot. An error maybe ?

Please submit this to the errata thread . Send me your address and I’ll mail you the correct pot. The instructions are very clear about which kind of pot goes into which position:

Add the 2x 100k pots with audio taper (resonance and main volume). An A is printed on the pot symbol on the PCB; and to identify the right part you can read “FA 100K” under the pot. If you are unsure which pot is which, check the resistance between the first and third lead before soldering them.

Check that the 100kA pot has not been soldered elsewhere - as it will cause a second problem.

I really paid attention when assembling the kit as it is my first “real” kit. I assembled it in 3 sessions as I have only few time to spend on this so maybe I didn’t pay enough attention to the pots…

I have checked (ohm meter) all the pots and only one is 100k. Every other is 10k. That’s why I think the kit only contained one 100k pot. There’s no prob, this can happen :slight_smile:

Thanx for your patience.